1. Field of the Invention
The present invention relates in general to a system for automatically opening and closing doors of vehicles by means of a switch equipped in the vehicle or a remote controller, and more particularly to a system for automatically opening and closing doors of vehicles which comprises a hydraulic pump and a pressure control valve, each connected to intermittent gearing assembly and operated in response to signals outputted from switch or the remote controller, thereby automatically opening and closing the doors and manually opening and closing the doors when the manual operation is required.
2. Description of the Prior Art
Known automatic door opening and closing system for vehicles is generally classified in accordance with the driving power source into two types, that is, an hydraulic cylinder type system in which an oil-hydraulic cylinder or a pneumatic cylinder is used for driving the door and a motor type system in which a chain gearing is used for transmitting the rotating power of a motor to the door. The one type of system provides a relatively high power to the door as a result of using the hydraulic power for the driving power so that this type of system is generally equipped in medium and large-size vehicles, such as medium and large-size passenger buses, having large and heavy doors, while the other type of system generates a relatively low power so that this type of system is generally used in a small-size passenger bus.
However regardless of the types, the known automatic door opening and closing system has a complex mechanism comprising a lot of elements such as for generating the driving power and transmitting the driving power to the doors. The system is thus obliged to occupy a substantial space inside the vehicles, thereby causing the spacial efficiency of the vehicles to be reduced. In result, such system has a disadvantage in that it is used within the limits of the middle or large-size vehicle which can provide an additional inner space for accommodating it, furthermore, it occupies a large part of the inner space of the vehicle as described above such that the casing enclosing this system generally juts out into the inner space of the vehicle and this causes the interior beauty of the vehicle to be spoiled.
In addition, during an automatic opening or closing operation of the door using the known automatic door opening and closing system, the system can not be manually operated to reverse the operation but continuously imparts the driving power to the door until the desired operation is accomplished. Therefore, if a person is sandwiched between the car frame and the door in the opening or closing operation, the person may be seriously injured by the door continuously imparted with the driving power by the system. On the other hand, if a hard foreign substance gets between the car frame and the door in operation, the car frame or the door is possible to be damaged.
The known automatic door opening and closing system is, therefore, not equipped in a small-size passenger vehicle such as a deluxe motorcar which provides a small inner space and takes a serious view of the interior beauty. Furthermore, almost the small-size vehicles such as the deluxe motorcars and the trucks are provided with integral type doors each of which is hinged to the car frame by hinged connections mounted between the car frame and a periphery of the door and is turned about the hinged connections to be opened or closed, while the buses are conventionally equipped with doors each of which linearly slides along the rails provided at the car frame or is folded at the vertical center line thereof simultaneously with turning about hinged connections provided between the car frame and the door. In result, there occurs a technical problem in employing the known system to the small-size vehicle having the aforementioned doors in consideration of the structure of the doors.
On the other hand, there has been proposed a door opening and closing system for small-size vehicles, for example, a system in which an expansion and contraction bar connected to the door and cooperating with an actuating lever, the lever being arranged adjacent the driver seat, expands or contracts in response to the driver's operation of the actuating lever to make the door be rotated about the hinged connections. However in this type of system, the doors are opened or closed by the driving power caused by the driver's operation of the actuating lever and simply transmitted from the actuating lever thereto by way of the expansion and contraction bar so that this system is not identified as a class of the automatic system but a manually operated system. Additionally, this system is conventionally equipped in the deluxe motorcars to allow the driver to manually open a back door for the passengers in the back seats so that it has a disadvantage in that it is inconvenient to open or close the door and may cause a serious traffic accident to occur due to a sudden opening of the door during a high speed running of the car.